Property  ol  the  United  States  Government 


'  03. 

I  aited  States  Department  o 

lU  of  knto 


It  urc, 


EQUIH    I 

Bj     I        II      I     III  I  II    Mil 

Entomologist  in  Chargi    of  /•'/■■ 
iNTRoni  <  pom  . 


A   moderate-sized   red   and   black   plant-bug,   variously   known   n- 
calico  back,"  "fire  bug,"  and  "terrapin  bug,"  a-  well  as  harlequin 


I 


M 


J 


■-#, 

n 


liar  lei] 

All 

;;il  I. 

cabbage  bug,  is  the  most   destructive  insect   enemy  of  cabbage  and 
related  crops  in  the  southern  part  of  the  United  States.     At  one  time 
it  was  a  serious  pest  northward  to  X>n  Jersey  and  westward  to  Ohio 
12066     fir.  108 


and,  indeed,  threatened  t<>  invade  New  York  and  New  England.  In 
recenl  years,  however,  its  progress  in  the  northern  State-  has  been 
checked  by  atmospheric  condition-. 

This  plant-bug  accomplishes  it-  work  of  destruction  by  sucking  the 
sap  from  leaves  and  reins  of  cabbage  and  other  crucifers,  the  af- 
fected plant-  wilting,  withering,  and  dying  as  if  they  had  been  swepl 
by  fire,  whence  the  name  "  fire  bug."  It  i-  a  pest  which,  if  permitted 
to  propagate  unmolested  in  seasons  which  favor  it-  increase,  i-  certain 
to  destroy  a  portion  if  not  all  of  the  fields  which  it  infests.  A  half 
dozen  mature  insects  are  capable  of  destroying  a  small  plan!  in  one 
or  two  days.  Some  year-  ago,  when  this  species  wa-  abundant  in 
the  vicinity  of  the  District  of  Columbia,  the  writer  saw  many  large 
fields  in  Maryland  and  Virginia  from  which  not  a  single  good  cab- 
bage could  he  picked,  and  observed  similar  injury  to  horse-radish 
and  some  other  crucifers. 

The  harlequin  bug  has  been  compared  to  the  boll  weevil  as  a  pest 
in  the  South  and  to  the  San  Jose  scale  as  a  scourge  in  New  Jersey. 
Certainly  it  is  to  the  cabbage  grower  what  the  other  two  insects  are 
to  the  cotton  planter  and  fruit  raiser  respectively.  If  growers  gen- 
erally, however,  will  undertake  the  method-  of  control,  a-  advised 
in  this  circular,  there  is  no  reason  why  it  should  be  longer  destructive. 

DESCRIPTIVE. 

The  name  harlequin  cabbage  bug  scarcely  requires  explanation  to 

any  one  familar  with  the  appearance  of  the  insect.  It-  gay  red  and 
black  ornamentation  is  suggestive  of  the  dress  of  the  <tage  harlequin. 
In  the  figure  of  the  adult  (fig.  1.  a)  the  dark  portions  illustrated  are 
either  black  or  dark  metallic  blue  and  the  light  portion-  are  bright 
yellow  in  freshly  transformed  bugs  and  red  in  fully  hardened  in- 
dividuals. 

The  eggs  (fig.  1.  h)  are  beautiful  objects  and  remarkable  for  the 
fact  that  they  closely  imitate  in  miniature  white  barrel-  bound  with 
black  hoops  and  with  black  spots  set  in  the  proper  place  for  bung- 
holes. 

The  younger  stages,  or  nymphs,  of  this  species  bear  considerable  re- 
semblance to  the  mature  form,  differing,  however,  in  the  lack  of 
wings  and  in  having  only  four  joints  to  the  antenna?,  whereas  the  adult 
has  five.  There  are  five  stage-  in  all.  illustrated  at  c,  </.  <.  f.  and  <j. 
In  the  third  and  fourth  nymphal  stage-  the  body  i-  hemispherical  and 
the  resemblance  to  a  turtle  or  terrapin  i-  striking. 

DISTRIBUTION. 

The  harlequin  cabbage  bug  i-  a  native  of  Mexico  and  Central 
America — where  it  obviously  originated — and  perhaps  also  of  the 
semitropical  regions  in  Texas,  Arizona,  and  New  Mexico.     It  was  lir-t 

[fir.  [03] 


3 

recorded  in  injurious  numbers  in  Texas,  in  Washington  <  ounty,  in 
1804,  and  -nice  then  has  traveled  gradually  northward,  although  nol 
with  uniform  rapidity.  Normally  the  species  is  | » i-<  >  1  >: 1 1  •  I  \  tropical  and 
has  been  diffused  through  two  additional  life  zones,  the  Lower  and 
Upper  Austral.  In  the  latter  zone,  however,  ii  has  not  become  pel 
1 1 1 ; 1 1 1 « * 1 1 1 1  \  established  much  farther  north  than  about  the  lower  or 
warmer  half.  The  region  about  Norfolk,  Va.,  "the  gateway  of  the 
South,"  i-  probably  the  northern  limit  of  actual  establishment  in  the 

A  year  >>r  two  following  its  discover]  .i    a  pest  this  species  had  in 
vaded  Louisiana,  and  bj   1867  was  recorded  from  North  Carolina.     [I 
spread  wa*  most   noticeable  along  the  Atlantic  seaboard  and  up  the 
\l  vsissippi   River  valley.     In   1870  it  had  appeared  in  Missouri  and 
Tennessee,  and  bj  1876  had  reached  Delaware.    In  Maryland  and  Vir 
ginia,  however,  it  did  not  attract  attention  until   lssn.     Ii   was  in  I 

recorded  as  injurious  in  Ne^  Jersey,  ;ii  W Ibury,  in  L892,1  and  in 

1804  ii  was  seen  at  Jamaica  and  "  Ne^  Lots  Road,'1  Nev    i  ork.' 

Westward  we  1 1 : i \ « •  office  records  of  n~  occurrence  in  Colorado  in 
ls^-_\  at  Pueblo  and'Denver,  but  it  1 1 .•  i -  never  been  an  important  pest 
in  that  region,  and  it  was  not  until  1S'-M*  that  it  was  recorded  in 
Indiana  and  not  till  1891  m  Ohio.  In  the  Latter  State  it  progressed 
steadily  northward  until  it  was  checked  by  the  same  atmospheric 
conditions  which  prevailed  in  the  Eastern  States  and  which  will  be 
mentioned  presently.  In  the  Pacific  region  the  species  is  well  estab 
lished  iii  southern  California,  but  there  seems  to  be  n<>  published 
record  of  the  time  of  its  firsl  appearance  in  that  State.  We  received 
specimens  from  San  Diego,  Cal.,  a-  early  as  lv7^.  The  insect  is  also 
recorded  from  Nevada. 

dispersion  of  tin-  species  in  the  Middle  States  has  been  traced 
li\  Mr.  I'.  M.  Webster,  and  from  what  has  just  been  stated  and  what 
has  been  placed  on  record  by  Messrs.  Webster  and  Howard  it  i-  very 

lent  that  it  has  becoi liffused  largely  by  what   Doctor  Howard 

terms  "commercial  jumps,'1  as  in  the  case  of  insects  like  the  aspara 
•ru^  beetle.  This  is  a  matter  quite  simple  of  accomplishment,  as  fertile 
egg  masses  can  be  carried  long  distances  mi  the  insect's  food  plants 
for  example,  on  the  outer  leaves  of  cabbages  bj  railroads  and  \>\ 
boat  It  will  be  noted  that  after  the  establishment  of  the  pest  in 
Delaware  it  did  not  attract  attention  farther  north  until  twenty 
years  later;  also,  that  other  introductions  were  made  in  different 
direction--  quite  independent  Iv  of  each  other. 

Recorded  bj  Gideon  Llncecum,  Practical  Entomologist,  Vol.  1,  p.  110,  Aug.  21, 

miner.  !»tii  Kept.  \..»   fork  State  Km.  f.  1802  i  1803),  pp.  316  317,  Ml. 
-   Tine,  Kul.  v..  New  Tori    kg     Exp.  Sta.  (Geneva),  Dec.,  1804,  p.  683. 

•    ...  Km.  Soc.  W.i-li..  Vol.  III.  pp.  288  -".hi.  1- 


To  recapitulate:  This  species  has  obviously  become  diffused  from  a 
central  point  of  dispersal,  Mexico,  chiefly  in  the  following  three  direc- 
tions: (1)  From  Texas  eastward  through  the  Gulf  States  and  north- 
ward along  the  Atlantic  seaboard  to  Long  Island;  (2)  from  Texas 
northward  through  the  Mississippi  Valley  and  thence  through  the 
Ohio  River  region  into  Ohio:  (3)  from  Mexico  into  the  neighboring 
States  and  Territories,  and  from  Lower  California  into  southern  Cali- 
fornia and  Nevada. 

The  northward  migration  of  the  harlequin  bug,  although  not  with- 
out interruption,  was  apparently  quite  steady  until  recent  years. 
Beginning  with  the  year  1897,  at  which  time  the  insect  had  reached 
its  maximum  as  a  pest  in  Maryland.  Virginia,  Delaware,  and  adjoin- 
ing States,  climatic  condition-  adverse  to  it-  existence  developed. 
These  consisted  of  sudden  changes  of  temperature,  such  as  cold  snaps 
followed  by  warm  -pells  and  the  reverse  during  the  winter.  As  a 
result  this  bug,  with  several  other  form-  of  southern  origin,  was  killed 
while  hibernating  and  practically  disappeared  in  the  North  until,  at 
the  date  of  writing  (1908),  it  i>  scarcely,  if  ever,  reported  a.-  in- 
jurious from  the  District  of  Columbia  northward.  These  conditions 
were  particularly  noticeable  in  the  winter  of  1898-99."  Small  scat- 
tering colonic-  are.  however,  occasionally  found  in  this  region,  chiefly 
on  wild  plants,  late  in  the  fall. 

LIFE    HISTORY. 

in  the  warm  and  equable  climate  of  the  South  where  this  species 
is  at  home  it  is  more  or  less  active  throughout  the  year.  Farther 
northward,  however,  after  the  first  severe  frosts  of  December  it  g 
into  hibernation  in  tufts  of  grass  or  under  rubbish  at  the  bases  of 
cabbage  -talks  or  in  any  convenient  place.  This  takes  place  chiefly 
in  the  adult  stage,  although  some  nymphs  of  the  last'  stages  remain 
afield  as  late  as  November  and  December.  Doubtless  the  nymphs 
succumb  in  time  to  cold,  and  hence  fail  to  survive  the  winter.''  The 
first  warm  days  of  February  or  March,  in  the  Gtdf  region,  or  of 
April,  farther  north,  see  the  bugs  appear  abroad  and  beginning  to 
feed.  At  first  wild  mustard  and  other  cruciferous  weeds  are  attacked 
and  soon  the  insects  are  ready  to  reproduce  their  kind.  On  these  wild 
plants  the  eggs  are  deposited,  on  end.  generally  in  two  more,  or  less 

'  Sec  r.ul.  22.  n.  s.,  Div.  Ent.,  T'.  S.  Dept.  Agric,  pp.  54,  55. 

6  A  number  of  adults  and  nymphs  in  the  last  two  stages  obtained  from  Lam- 
bert's Point,  Va.,  October  21.  1907,  were  placed  in  a  rearing  cage  with  growing 
cabbage  plants,  grass,  and  similar  rubbish  to  provide  moans  of  hibernation.    For 

over  a  mouth  or  until  some  time  in  December  the  insects  continued  feeding,  but 
when  examined  duriag  the  lirst  week  of  March  it  was  found  that  all  had  suc- 
cumbed to  the  severe  cold  weather  of  February. 
[Cir.  L03] 


parallel  rows  cemented  together  in  groups  of  about  :i  dozen,  .1  shown 
iii  figure  l.  The)  are  normal!)  placed  on  the  under  ridi  "I  the  lea 
and  hatch,  in  warm  weather,  in  three  or  four  days  after  deposition 
and  in  five  i"  eighl  days  in  the  cooler  weather  of  earl)  spring.  The 
young  bugs  or  nymphs  pass  through  their  five  tages  of  metamor 
phosis  with  considerable  rapidity.  It  has  been  stated  thai  the  life 
cycle  could  be  completed  in  warm  weather  in  about  two  weeks,  but 
this  is  "l>\  iously  ;in  exaggerat  ion,  as  ii  requires  four  or  five  weeks  for 
the  completion  of  the  cycle  in  related  insects. 

The  life  periods  <>f  tin-  species  were  unknown  until  worked  out 
bj  Mr.  II.  ( ).  Marsh,  of  this  office.  Specimens  (from  Texas)  were 
under  observation  from  the  first  week  "I  March  until  the  first  week 
of  May.  The)  were  under  somewhat  unnatural  conditions,  being 
confined  in  our  office  room,  which  was  maintained  during  this  period 
hi  :m  average  temperature  of  from  68  i"  70  F.  The  first  or 
stage  i«'\  civ<|  1 1  days.  The  time  from  the  hatching  of  the  eggs  until 
tin  firsi  molt  gave  the  first  larval  instar  or  nymph  period  7  days; 
the  second  instar  required  13  days;  the  third,  s  days;  the  fourth,  II 
days,  while  tin-  fifth  or  pupal  instar  covered  17  days  a  total  of  70 
days,  or  lo  weeks,  in  all,  which  will  be  not  far  from  the  maximum 
active  period  of  this  species.  The  minimum  will  probably  fall  into 
much  lower  figures,  probably  half  of  this  time,  or  ni  most  not  more 
than  I-'  days  in  extremely  hot  midsummer  weather. 

When  cabbage  and  similar  plants  come  up  the  insects  migrate  to 
them.  It  has  been  surmised  that  owing  to  the  rapid  development  of 
the  cabbage  bug  in  the  South  there  is  a  possibility  of  as  man)  as  seven 
or  eight  generations  each  year,  while  in  the  Ninth  three  or  more  occur. 
The  first  supposition  is  doubtless  overdrawn,  as  we  know  of  no  simi- 
lar insect  producing  so  many  generations  annually.  This  is  a  prob- 
lem for  future  study.  It  seems  probable  that  four  or  five  generations 
would  be  a  more  natural  limit   in  the  South  and   two,  or  possibly 

three,  in  the   North. 

POOD   PI   \  \  I  S. 

Iii  the  autumn  after  the  cabbage  crop  has  been  made  and  in  early 
winter,  even  as  far  north  as  Washington,  the  bugs  are  -till  afield, 
seeming  loath  to  seek  shelter  for  the  cold  months.  At  this  time  they 
cluster  on  cabbage  -talk-  and  sprouts  and  the  leaves  of  turnip  and  like 
plant-,  and  when  the  supply  of  crucifers  has  become  exhausted  they 
will  attack  almost  any  form  of  succulent  tion  which  i-  most 

available  and  palatable. 

On  one  farm  the  writer  observed  a  field  of  10,000  cabbage  plants 
completely  ruined,  which  at  the  time  of  his  visit,  the  first  week-  in 
October,  hail  been  deserted  by  the  bugs.     An  adjoining  field  of  pota- 


toes  was  then  attacked,  afterwards  one  of  eggplant,  and  numerous 
bugs  in  various  stages  were  observed  sucking  the  juices  of  these 
plants.  Unripe  fruit  of  eggplant  was  especially  relished,  and  ripe 
pods  of  okra  and  beans  were  also  attacked. 

The  list  of  useful  plants  which  this  species  has  been  found  to 
damage  include-  all  form-  of  crucifers  or  cole  crops — cabbage  and 
related  plants,  kale,  collards  and  cauliflower,  turnips,  radish,  horse- 
radish, mustard,  rape,  and  the  like — and  when  these  crop-  have  been 
killed  out  truck  crops  of  nearly  all  kinds  are  attacked,  of  which  egg- 
plant, asparagus,  potatoes,  tomatoes,  okra.  beans,  and  licet-  arc  mos( 
affected.  Damage  is  sometimes  done  to  ornamental  plants  such  as 
roses,  sunflowers,  and  chrysanthemums  in  flower  gardens,  and  Mr. 
J.  M.  Rankin,  while  an  agent  of  this  Bureau  at  Chico,  ('ah.  in  Octo- 
ber, 190."),  reported  that  this  species,  after  entirely  destroying  a  half- 
acre  plat  of  cabbage,  attacked  the  other  plant-  in  the  vicinity,  includ- 
ing nursery  plants  of  citrus,  loquat,  cherry  and  plum,  squash.  e<r^r- 
plant,  "  and  in  fact  everything  green."  The  fruit  of  "tape-  and 
late  corn  has  also  been  attacked.  The  bugs  are  very  partial  to  rag- 
weed (Ambrosia),  pigweed  (Amarantus),  wild  lettuce  (Lactuca 
canadensis),  and  lambsquarter  (Chenopodium),  congregating  on  all 
parts  of  the-e  weeds  but  appearing  to  prefer  the  stems. 

The  wild  food  plants  on  which  the  species  actually  breeds  include 
wild  mustard  and  cresses  of  different  kinds,  shepherd's  purse,  pepper- 
grass,  bitter-cress,  rock-cress,  and  practically  all  other  plants  of  the 
mustard  family  (Cruciferae)  as  well  a-  some  of  the  closely  related 
caper  family  (Capparidacese). 

NATIliAI.  ENEMIES. 

The  comparative  freedom  from  the  attack  of  natural  enemies 
-which  the  harlequin  cabbage  bug  enjoys  is  remarkable,  and  is  due  to 
two  causes:  First,  to  the  warning  type  of  its  coloration — black  and  red 
or  yellow;  and,  second,  to  its  distasteful  odor  and  flavor.  This  latter 
has  been  tested  frequently.  In  the  writer"-  experience  birds  that 
would  attack  most  common  insects  would,  when  offered  one  of  these 
bug-,  either  peck  at  it  or  look  at  it  askance,  or  if  by  chance  they  ate 
a  bug  they  did  not  repeat  the  close. 

Nevertheless  the  insect  has  one  effective  natural  enemy,  a  minute 
parasite,  Trissolcus  murgantia,  Ashm..  which  develop-  in  the  egg 
Prof.  H.  A.  Morgan  when  in  Louisiana  discovered  that  out  of  over 
a  thousand  eggs  under  observation  in  1902  nearly  all  were  killed 
by  this  useful  little  creature.  The  eggs  are  also  attacked  by  Ooen- 
cyrtiis  johnsoni  How.  and  have  been  parasitized  artificially  by  7 
solcus  podisi  Ashm. 

[Cir.  103] 


This  -|"  .il-'i  preyed  upon  l>\   another  bug,    Irilm 

I...  the  wheel  bug,  which  the  writer  has-  frequently  seen  attacking  the 
ybung  harlequins. 

The  influence  of  natural  elements,  particularly   cold   winfc 
already  been  mentioned  as  a  means  of  decimating  this  pest.     Ii  i-  well 
to  add,  however,  that  the  writer  had  this    pecies  under  close  ob 
\;iiioii  in  1899,  and  thai  ;i-  a  resull  of  sudden  cold  snaps,  Bo  per  cenl 
of  the  bugs  in  fields  near  Washington  in  thai  year  had  been  killed  by 
January   15,  I! 

\il   rilODS    "l     fMINTROL. 

The  experience  of  years  has  shown  thai  in  order  t"  obtain  the  besl 
results  In  the  treatment  of  the  harlequin  cabbage  bug  preventives  are 
necessary,  as  there  is  great  difficulty  in  obtaining  insecticides  which 
are  effective  and  which  do  no1  ;ii   the  same  time  injure  or  kill  the 
plants.     These   preventives  are:   <ii   Clean  cultural   methods,  espe 
cially  in  the  fall :   (2)  the  use  of  trap  crops  of  mustard  or  other  plants 
in  i In-  spring, and  i  :'>  i  hand  methods.     With  stricl  observance  of  clean 
fanning  few  of  the  insects  will  survive  the  following  spring  and  I 
adoption  of  trap  crops  leaves  fewer  still  to  be  desl  royed  by  mechanical 
measures.     In  some  cases  :ill  three  methods  shoidd  be  adopted,  foi 
they  are  neglected  the  grower  will  find  it  n  mosl  vexatious  matter  to 
control  the  pe-t  iii  the  midsl  of  the  growing  season. 

Clean  cultural  methods.     Of  prime  importance  are  clean  cultural 

methods.    The  value  of  clean  methods  ol  farming  has  1 n  recognized 

by  nearly  everyone  who  has  had  experience  with  this  insect.  The 
practice  of  leaving  -talk-  of  cabbage  and  oilier  cruciferous  plant-  in 
the  field  late  in  the  autumn  and  in  the  early  winter,  or  of  permitting 
rank  weeds  to  grow  up,  or,  in  fact,  allow  ing  an\  sorl  of  debris  to  accu- 
mulate, serves  as  a  mean-  of  protracting  the  life  of  this  insect,  as  all 
such  materia]  either  affords  it  food  late  in  the  season  or  quarters  for 
protection  against  the  elements  during  winter.  It  is  even  inad 
visable  to  plant  crucifers  in  the  vicinity  of  outhouses  and  barns, 
the  hue;-  are  apt  to  enter  these  latter  for  passing  the  winter. 

Throughoul  the  year  wild  plant-  of  the  mustard  family,  on  which 
the  insecl  chiefly  breeds,  should  be  carefully  kept  down  nol  only  in 
the  fields  but  in  the  immediate  neighborhood.    A  li-t  of  such  plan; 
given  on  page  6. 

Tiii/i  ■  rops.  Some  plant-,  such  a-  cabbage,  turnip,  or  kale,  may  be 
planted  late,  to  be  lefl  at  interval-  throughout  infested  fields.  These 
trap  plants  attract  the  insects  in  the  fall,  and  here  the  latter  may  be 
killed  with  pure  kerosene,  or  by  mechanical  methods.  Where  it  is  con- 
venient to  leave  piles  ^i  rubbish  until  the  insects  are  attracted  to 
them  this  may  be  done,  and  the  entire  material,  insects  and  all.  should 
then  be  burned. 

H'ir.  10S] 


8 

The  best  remedy,  however,  and  one  that  should  be  put  into  opera- 
tion by  every  cabbage  grower  who  is  troubled  by  this  pest,  consists  in 
planting  an  early  crop,  which  may  be  either  mustard,  rape,  or  kale, 
as  a  lure  for  the  first-appearing  insects.  Radish  and  turnip  serve  a 
similar  purpose.  In  the  Gulf  State-  the  overwintered  adults  appear 
in  February  and  March,  and  in  the  District  of  Columbia  and  vicinity 
in  the  latter  part  of  April.  For  some  reason  they  appear  to  prefer 
the  plant:-  that  have  been  enumerated,  and  wild  mustard  and  other 
crucifers,  for  the  first  deposition  of  their  c^ii-.  On  these  crops  and 
on  weeds  the  insect-  can  he  killed  with  kerosene  or  by  the  hand  torch 
or  may  he  collected  in  nets,  or  they  may  be  destroyed  by  burning  the 
entire  trap  crop  when  this  is  of  no  special  value.  Numerous  reports 
have  been  received  at  the  Department  of  Agriculture,  and  other-  have 
been  recorded,  of  the  value  of  trap  crops  a-  a  mean-  of  controlling 
this  pest.    Some  of  these  are  worth  repeating. 

The  first  test  of  the  trap-crop  remedy  wa-  made  by  Lincecum 
(1.  C.)  in  Texas-,  in  L866.  Noticing  that  the  buy-  were  numerous  on 
mustard  and  radish  in  April,  he  handpicked  them  and  thus  protected 
his  cabbage  crop.  The  practical  utility  of  this  method,  however,  does 
not  appear  to  have  been  recognized  until  considerably  later.  In 
1891,  Mr.  II.  F.  Weed,  when  entomologist  of  the  Mississippi  Agri- 
cultural Experiment  Station,  -owed  a  row  of  mustard  through  the 
center  of  a  1-acre  field  of  cabbage.  In  April  this  mustard  attracted 
the  bugs  in  large  number-  and  on  it  they  were  killed  with  undiluted 
kerosene,  with  the  result  that  throughout  that  season  the  field  re- 
mained free  from  the  pest,  whereas  the  previous  year  the  cixjp  was 
almost  entirely  destroyed." 

Hand  methods. — If  determined  effort-  are  made  to  stamp  out  the 
first  generation  fewer  insects  will  remain  to  be  dealt  with  and  very 

°A  correspondent,  Mr.  J.  II.  Hevey,  ingomar,  Miss.,  tested  the  trap-crop 
remedy,  and  wrote  that  when  the  bugs  made  their  appearance  on  a  bed  of  mus- 
tard ho  destroyed  them  by  "  bugging,"  i.  e.,  by  shaking  them  into  pans  of  water 

on  which  a  thin  film  of  kerosene  was  floating.  When  the  mustard  was  removed 
to  make  room  for  another  crop  a  few  cabbage  plants  became  infested,  but  the 
bugs  were  killed  as  above,  and  finally,  after  the  middle  of  July,  none  was  left. 

One  of  the  largest  mowers  of  cabbage  in  Delaware  reported  (Sanderson, 
Hill.  26,  n.  s..  Bur.  Knt..  U.  S.  Dept.  Agric,  p.  67,  1900)  that  at  .me  time  it  was 
impossible  to  raise  cabbage  on  account  of  this  pest,  hut  for  several  years  In- 
had  used  kale  as  a  trap  Crop,  and  as  a  result  of  this  procedure  and  careful 
handpicking  of  the  few  bugs  that  strayed  to  the  cabbage,  he  had  been  troubled 
very  little,  while  his  neighbors'  cabbage  had  frequently  been  ruined. 

In  April  of  one  year  in  Maryland  half  an  acre  of  kale  became  freely  infested 
on  one  side  by  harlequin  bugs.  The  insects  had  all  congregated  on  this  side. 
Under  the  writer's  direction  this  portion  was  burned,  straw  being  used  to 
facilitate  ignition.  Two  weeks  later  not  a  single  bug  could  he  found  in  a  walk 
about  this  patch,  and  the  cabbage  which  was  growing  in  several  plats  in  tiie 
vicinity  was  tree  from  injury. 
[Cir.  103] 


9 

I'i'w  will  ilv  from  other  quarters  for  the  continuation  of  the  speci 
Thus  injur)  maj  be  great h  curtailed  if  not  absolutely  prevented  foi 
:in  entire  season.  The  large  size  and  bright  colors-  "I'  the  insecl  render 
ii  easj  of  detection  and  its  sluggish  nature  h  isl  in  il  easj  capture. 
Mr.  II.  Walter  McWilliams,  Griffin,  Ga.,  reports  thai  bj  offering 
a  liiiiini\  in  school  children  for  the  destruction  "I  this  pesl  he  sue 
ceeded,  in  March  and  April,  1902,  in  destroying  the  first  general  ion  in 
thai  vicinity,  and  estimated  thai  this  experiment  saved  him  $100  <>n 
his  cabbage  crop  alone,  not  counting  the  benefil  to  the  children. 

As  instance  of  the  ease  with  which  this  insecl  may  !»•  hand-picked, 
rower  m   Denton,  Tex.,  gathered,  in  February  of  one  year,  17,000 

bugs.     In  case  hand-picking  has  nol  I n  thoroughly  done  and  some 

bugs  have  escaped  this  process  and  succeeded  in  depositing  their  eggs, 
the  masses,  which  maj   be  easily   recognized  l«\  comparison  with  fig 
are  I,  ;'.  should  I arefully  gathered  and  crushed. 

Kerosem  emulsion^  according  to  the  testimony  of  many  who  have 
experimented  with  it.  is  nol  effective  against  the  adults  and  only  par 
tially  effective  when  sprayed  on  the  younger  nymphs.  Quite  recently 
Prof.  A.  F.  Conradi  !  has  found  thai  i  L0  per  cenl  kerosene  emulsion 
i-  effect  ive  in  killing  the  nymphs,  as  i-  also  whale-oil  -nap.  at  the  rate 
of  2  pounds  to  I  gallons  of  wain.  It'  the  insects  are  sprayed  j 
after  they  have  molted  these  insecticides  almost  invariably  kill  them. 
It  is  obvious  that  further  experimentation  is  desirable  along  this  line. 

Of/i,  r  ri  im  1 1  ii  8.  A  few  words  should  !><•  said  of  other  remedies  and 
may  be  prefaced  with  the  remark  thai  since  the  harlequin  cabbage 
bug  feeds  exclusively  by  suction  and  does  nol  chew?  it-  food,  the  ar 
senicals,  hellebore,  and  such  remedies  as  are  useful  against  cabbage 
worms  are  absolutely  valueless  against  the  present  species.  Pyre 
thrum  is  nol  effective  and  is, moreover, too  costly.  I !<>t  water  applied 
at  a  temperature  of  aboul  130  1".  to  the  infested  cabbage  plants  should 
be  tested.  It  i-  nol  applicable,  however,  t"  large  fields  on  account  of 
the  difficulty  of  maintaining  tin'  temperature  at  a  given  point,  hut 
may  he  found  useful  in  kitchen  gardens. 

The  value  of  hand  torches  for  insecticidal  purposes  i-  extremely 
limited.  The  plumbers1  torch  i-  used  considerably  in  Texas  a-  a 
means  of  killing  this  insect,  but  growers  an-  a]  t  to  expect  too  much 
of  tlii  —  method,  and  to  apply  it  to  too  many  kinds  of  insects,  to  the 
ultimate  detriment  of  their  crops. 

It    i-  possible  that   some  id'  the  natural  enemies  of  this  sp 
especially  southern  egg  parasites,  might  he  utilized  in  its  control;  i.  <•.. 
by  shipping  parasitized  eggs  from  localities  where  thej  are  abundant 
to  northern  regions  in  which  thev  do  not  occur. 


Bi      9      i  •  Exp.  st:i..  pp.  '.•  11.  1007. 

Kir.  103] 


10 

M   M  MARY. 

The  genera]  acccount  which  has  been  given  of  this  insect  in  preced- 
ing pages  has  been  brought  together  at  this  time  because  of  the  practi- 
cal certainty  that  in  the  natural  course  of  events  this  bug-  will  before 
long  endeavor  to  reinvade  territory  north  of  it>  present  range  (in 
L908),  and  may  again  become  a  pest  for  a  number  of  years,  until 
climatic  condition-  adverse  to  it-  development  or  increase  check  its 
northward  spread. 

///  conclusion,  it  should  be  repeated  that  the  systematic  destruction 
of  the  insects  by  mean-  of  the  trap-crop  method  described,  together 
with  a  system  of  clean  cultural  practice  throughout  the  entire  season 
and  especially  in  the  late  fall,  will  leave  little  else  to  he  done  save  the 
gathering  by  hand  of  such  insects  a-  escape  these  measure-  or  which 
may  fly   from  infested  to  uninfe-ted  iields. 

T<>  prevent  tin'  pest  from  advancing  farther  northward  thai,  its 
present  limits,  careful  watch  should  be  kept  for  flu  fist  appearance 
of  tl,c  insect,  and  remedies  should  be  prompt  and  thorough.  The  im- 
portance of  killing  off  the  lir-t  or  hibernated  brood  of  bugs  and  their 
progeny  can  not  be  too  strongly  emphasized. 

Approved: 

James  Wilson, 

Secretary  of  Agriculture. 

Washington,  D.  C,  May  4,  1908. 

[Cir.  L03] 

o 


• 


3     1262    05252    3460 


MARSTON  SCIENCE  LIBRARY 


Date 

Due 

Due 

Returned 

Due 

Returned 

' 

UNIVERSITY  OF  FLORIDA 


3  1262  09216  5520 


